# Jolt

> Jolt is a Clojure implementation on Scheme. It reads Clojure source, analyzes
> it to a host-neutral IR, emits Scheme, and runs it: on Chez by default, or on
> Gambit compiled to JavaScript for the browser. The compiler is self-hosted,
> written in Clojure and compiling itself, and ships a Clojure-compatible
> standard library. Programs compile to single self-contained native binaries
> with no JVM and no runtime install.

Important: there is no JVM underneath Jolt, so JVM reasoning does not carry
over. Most portable Clojure runs unchanged (persistent collections, the numeric
tower (including `BigDecimal`), lazy seqs, transducers, protocols/records,
multimethods, metadata, atoms, refs/STM, `future`/`promise`/`agent`/`pmap`,
`core.async`, runtime `eval`, and the full reader). What differs: there is no Java
interop (no reflection, no `gen-class`/`proxy`; `Class.`/`Class/static`/`.method`
resolve only against a shimmed subset of `java.*` written in Scheme, and a class
token is a name, not a loaded class); those shims implement their JVM
counterparts' API but not the JVM's runtime, so classloaders, JVM GC behaviour,
and JVM thread-lifetime rules do not apply; strings are codepoint-indexed rather
than UTF-16, so `(count "😀")` is 1; regexes compile through irregex, not
`java.util.regex`; and `clojure.core` coverage is broad but not total. C
libraries are reached through the `jolt.ffi` foreign-function interface.
Read the Differences page before assuming a JVM behaviour holds.

## Start here

- [Getting Started](https://jolt-lang.github.io/docs/getting-started.html): install, evaluate, run a project, dependency requirements per platform.
- [Differences from Clojure](https://jolt-lang.github.io/docs/differences.html): the divergences from JVM Clojure. Read this first when porting code.
- [Rationale](https://jolt-lang.github.io/docs/rationale.html): why a Clojure on Scheme, and what it is for.
- [Source repository](https://github.com/jolt-lang/jolt): the compiler, runtime, and standard library.

## Guides

- [Building & Running](https://jolt-lang.github.io/docs/building-and-deps.html): `deps.edn` projects, AOT compilation to a native binary, typed arithmetic and inference.
- [REPL-Driven Development](https://jolt-lang.github.io/docs/repl-driven-development.html): the nREPL server and editor setup (CIDER, Calva, Cursive).
- [Writing Libraries](https://jolt-lang.github.io/docs/writing-libraries.html): publishing a jolt library, the `.jolt`/`.cljc` extension rules.
- [Testing](https://jolt-lang.github.io/docs/testing.html): `clojure.test` on jolt and how the conformance corpus works.
- [Host Interop](https://jolt-lang.github.io/docs/host-interop.html): which `java.*` classes are shimmed, and how to register your own host classes.
- [Native Interop (FFI)](https://jolt-lang.github.io/docs/native-interop.html): binding C shared libraries with `jolt.ffi`, and exporting jolt code behind a C ABI.
- [Cljc Interop](https://jolt-lang.github.io/docs/cljc-interop.html): sharing source with JVM Clojure and ClojureScript.
- [Fibers](https://jolt-lang.github.io/docs/fibers.html): lightweight concurrency.
- [Extension Points](https://jolt-lang.github.io/docs/extension-points.html): the registries jolt exposes for libraries to extend.
- [Numeric Performance](https://jolt-lang.github.io/docs/numeric-performance.html): unboxed flonum/fixnum arithmetic and type hints.
- [Scheme Backends](https://jolt-lang.github.io/docs/scheme-backends.html): Chez versus Gambit, and the browser build.
- [Libraries](https://jolt-lang.github.io/docs/libraries.html): the ported and native library ecosystem.

## API reference

- [Dependencies (jolt.deps)](https://jolt-lang.github.io/docs/api/deps.html)
- [Foreign Functions (jolt.ffi)](https://jolt-lang.github.io/docs/api/ffi.html)
- [File System (babashka.fs)](https://jolt-lang.github.io/docs/api/fs.html)
- [Program Images (jolt.image)](https://jolt-lang.github.io/docs/api/image.html)
- [Date & Time (jolt-lang/time)](https://jolt-lang.github.io/docs/api/time.html)
- [Parser Combinators (jolt.parser)](https://jolt-lang.github.io/docs/api/parser.html)
- [Infix Notation (jolt.infix)](https://jolt-lang.github.io/docs/api/infix.html)
- [Utilities (jolt.util)](https://jolt-lang.github.io/docs/api/util.html)

## Reference and internals

- [Language Specification](https://jolt-lang.github.io/docs/spec/README.html): the reader, special forms, and per-function `clojure.core` coverage.
- [deps.edn Internals](https://jolt-lang.github.io/docs/tools-deps.html): how dependency resolution works without Java.
- [RFCs](https://jolt-lang.github.io/docs/rfc/README.html): design notes on transients, type hints, structural inference, success-type checking, compilation modes, program images, the portable Scheme layer.
- [Module Map](https://jolt-lang.github.io/docs/MODULES.html): what each runtime and compiler file does.
- [Seed & Overlay Registry](https://jolt-lang.github.io/docs/seed-overlay-registry.html): what is baked into the bootstrap seed versus loaded at runtime.